Heat treatment method for reducing steel casting processing surface weld seam hardness

Abstract

The invention discloses a heat treatment method for reducing the steel casting processing surface weld seam hardness. The heat treatment method for reducing the steel casting processing surface weld seam hardness comprises the steps of firstly selecting an argon arc welding filling wire for filling and repair-welding a workpiece concave pit, wherein the repair-welding is required to be carried outaccording to the process parameters that the interpass temperature is controlled to be 270 to 350 DEG C, the welding current is controlled to be 150 to 180A, the gas tungsten arc welding (GTAW) protection gas is 99.999 percent of Ar gas, the flow is 10 to 18L / min, and the welding layer number is 2 to 4 layers; adopting direct-feeding welding walking, repair-welding in lanes layer by layer, and removing the surplus height of a weld seam after flushing; and after accomplishing the step 1, continuously and additionally welding a layer of TIG remelting weld layer above the weld seam, adopting same process parameters, and then remelting and carrying out heat treatment, wherein the remelting current is 180 A, and the voltage is 17V, the direct-feeding welding walking is adopted for remelting, and the width of a remelting weld pass does not exceed 7mm. According to the heat treatment method for reducing the steel casting processing surface weld seam hardness provided by the invention, a surface weld pass remelting technology is adopted, no extra equipment is needed, the method is simple and convenient to operate, the hardness of the weld seam can be remarkably reduced, the treated product is non-deforming and non-oxidizing, the production efficiency is improved, and the dimensional deviation caused by vacuum heat treatment of fine processing products is effectively prevented.

Description

technical field [0001] The invention relates to the field of post-weld heat treatment, in particular to a new method for reducing the hardness of a weld seam on a B50A178H processed surface by a novel post-weld heat treatment method. Background technique [0002] In the finishing stage of B50A178H castings, unacceptable small defects such as trachoma, pores, cracks, etc. appear. After eliminating the defects and repairing welding, the reduction of hardness can be achieved by tempering weld bead technology or overall vacuum heat treatment. [0003] The tempering weld bead technology in the prior art reduces the hardness, which is complicated and difficult to master, and the effect of reducing the hardness is not stable. The overall vacuum heat treatment equipment is very expensive, and the equipment has limitations on the size of the product, and at the same time consumes time and energy. During vacuum heat treatment, the product undergoes high-temperature heat treatment and...

AI Technical Summary

Problems solved by technology

[0003] The tempering weld bead technology in the prior art reduces the hardness, the technology is complex and difficult to master, and the effect of reducing the hardness is unstable

The overall vacuum heat treatment equipment is very expensive, and the equipment has size limitations on the product, and at the same time consumes time and energy

During vacuum heat treatment, the product undergoes high-temperature heat treatment and there is a risk of dimensional deformation, which is not suitable for high-precision product processing surface repair welding hardness reduction

Since it is impossible to achieve absolute vacuum in vacuum heat treatment, the surface of the product will be slightly oxidized during heat treatment, which will affect the surface brightness

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